1. Field of the Invention
This invention relates to a hearing aid and, in particular, to a hearing aid including sound replay capability.
2. Related Art
FIG. 1 is a block diagram of a conventional analog hearing aid 100. The hearing aid 100 is mounted on a wearer on, in, or proximate to an ear of the wearer to assist the wearer in hearing. The hearing aid 100 includes a microphone 101 that is adapted to sense sound in the vicinity of the hearing aid 100 (and, thus, in the vicinity of the wearer) and convert the sensed sound to electrical signals. (The hearing aid 100 could also be implemented to include a receiver instead of, or in addition to, the microphone 101, signal(s) representing sensed sound being transmitted to the receiver by one or more transmitter(s) that are typically positioned at location(s) that are not proximate to an ear of the wearer of the hearing aid 100.) The electrical signals produced by the microphone 101 (and/or received by a receiver) are input to a filter 102 which processes the electrical signals to remove undesirable artifacts. The filtered electrical signals from the filter 102 are input to an amplifier 103 which amplifies the electrical signals to produce an amplified electrical signal that is compatible (as understood by those skilled in the art) with the speaker 105 (described later). The amplified electrical signals from the amplifier 103 are input to a filter 104 which processes the amplified electrical signals to further remove undesirable artifacts. A speaker 105 receives the electrical signals from the filter 104 and produces sound in accordance with the electrical signals, thereby reproducing sound that occurs in the vicinity of the wearer. In particular, as is well understood, the hearing aid 100 reproduces sound that occurs in the vicinity of a wearer so as to facilitate hearing of that sound by the wearer. (Though the filter 102 and the filter 104 are described above as part of the hearing aid 100, those skilled in the art will understand that a conventional analog hearing aid, such as the hearing aid 100, need not necessarily include a filter such as the filter 102 and/or a filter such as the filter 104. Additionally, those skilled in the art will understand that, though the filters 102 and 104 are illustrated in FIG. 1 separate from other components of the hearing aid 100, the filter 102 can be implemented in the same apparatus as the microphone 101 (and/or receiver) or the amplifier 103, and/or the filter 104 can be implemented in the same apparatus as the amplifier 103 or the speaker 105.)
FIG. 2 is a block diagram of a conventional digital hearing aid 200. As the hearing aid 100 of FIG. 1, the hearing aid 200 is worn by a wearer to assist the wearer in hearing. The hearing aid 200 includes a microphone 201 (and/or receiver), filters 202 and 204, and a speaker 205 which provide the same or similar functionality as that described above for the microphone 101 (and/or receiver), filters 102 and 104, and speaker 105, respectively, of the hearing aid 100. (Like a conventional analog hearing aid, a conventional digital hearing aid, such as the hearing aid 200, need not necessarily include the filter 202 and/or the filter 204.) In the digital hearing aid 200, the filtered electrical signals from the filter 202 are input to an A/D converter 206 to convert the analog electrical signals produced by the microphone 201 (and/or received by a receiver) and processed by the filter 202) to digital electrical signals. The digital electrical signals from the A/D converter 206 are input to a digital processing unit 203 which processes the electrical signals, as described further below, to produce a processed electrical signal having desired characteristics and compatibility with the speaker 205. The processed electrical signals from the digital processing unit 203 are input to a D/A converter 207 to convert the digital electrical signals to analog electrical signals that can be used by the speaker 205 to produce sound. (Though not illustrated in FIG. 2, the hearing aid 200 may also include an amplifier between the D/A converter 207 and the speaker 205 to amplify the electrical signals to have a magnitude compatible with the speaker 205, as understood by those skilled in the art.)
As indicated above, the digital processing unit 203 of the hearing aid 200 processes the electrical signals. In particular, the digital processing unit 203 can be implemented to selectively process the electrical signals based on the magnitude of the electrical signals and/or the frequencies contained in the electrical signals. The digital processing unit 203 can include a digital signal processor (DSP), as known to those skilled in the art, which can be implemented to accomplish the above-described functionality of the digital processing unit 203. The digital processing unit 203 can also include other devices (e.g., a memory device) in addition to the DSP to facilitate the operations of the DSP.
Conventional hearing aids have been produced in a variety of sizes and shapes, but, as can readily be appreciated, all hearing aids must be, or preferably are, constructed to be relatively small apparatus. Until recently, manufacturing capabilities have limited the ability to include functionality in a hearing aid in addition to that described above without causing the hearing aid to be larger than is desirable for some applications and/or people. In the same vein, the small size of hearing aids necessitates the use of a relatively small power supply (e.g., battery), which has also limited the ability to include functionality in a hearing aid in addition to that described above.